Process of manufacturing waterproof crepe-paper



Patented Oct. 2, 1934 1,975,286 raooass or MANUFACTURING WATER.-

PROOF CREPE-PAPER Friedrich Moritz Otto Pinofi, London, England,assignor, by mesne assignments, to The Patent and Licensing Corporation,New York, N. Y., a corporation of Massachusetts No Drawing.

Application December 5, 1931,

4 Serial No. 579,347. In Germany December 10,

, 1930 2 Claims.

The invention relates to the manufacture of waterproof orwater-impermeable crepe-paper with the aid of aqueous dispersions ofasphalt, paraflin, wax or similar water-repellent sub-. stances.

Waterproof or water-impermeable crepe-pa' per has hitherto beenmanufactured by applying molten asphalt or the like to a sheet of paperand creping the paper on a roll by means of a scraper or doctor incontact with the roll. When the paper is made in this manner, it isneces-.

sary that the asphalt be heated or treated with solvents in order tobring it to an adhesive state. It is furthermore essential that the faceof the paper to which the asphalt is applied be brought into contactwith the creping roll in order to cause the paper to adhere theretoduring the creping operation.

In the manufacture of crepe-paper comprising several layers, whereasphalt or the like is placed between two adjacent layers in order tomake the product impermeable to water, the paper obtained according tothe known process is indeed creped on both sides. However, all thecavities between the two layers of paper are necessarily filled withasphalt and consequently an extremely large quantity of asphalt or thelike substance is required. The asphalted crepe-papers thus produced nolonger constitute crepepapers proper, since they cannot be pulled out,which is an essential property of crepe-paper. Moreover they have thedrawback of being extremely susceptible to changes in temperature onaccount of their high content of asphalt or the like, whilst, moreover,they cannnot be produced in thin sheets. As a result these products haveno practical importance.

It has now been found that these drawbacks,

viz. the necessity of bringing the water-repellent material, while hot,into contact with the creping roll, the consumption of considerablequantitles of water-repellent substance and the reduced elasticity ofsuch creped papers, canbe avoided by using the water-repellent substancein the form of an aqueous dispersion during the creping process. In theproducts thus obtained the layer of water-repellent substance is of auniform thickness throughout and the shape of this layer is practicallythe same as that of the oreped paper.

In general the creping is done by bringing the paper, while adhering toa roll, into contact with a scraper or doctor, whereby it is crinkledand folded. For this purpose it is necessary that the paper sticks tothe roll, as otherwise the crinkling action does not take place. Inorder to effect such adhesion the creping may preferably be carried outon wet paper, and therefore a new and technically important effect ofthe use of the water-repellent substance in dispersed form consists inthat the water of the dispersion serves for bringing the requiredmoisture into the paper. When providing either a finished, previouslydried paper web, or a semifinished, not or incompletely dried paper web,with an aqueous dispersion of water-repellent substance the paperabsorbs the water of .the aqueous dispersion at the moment of its beingbrought into contact with the dispersion and 'is thereby capable ofbeing pressed onto the creping roll with such adhesiveness as isrequired for the subsequent .crinkling and folding bymeans of thescraper. In principle it is then immaterial which side of the paperprovided with an aqueous dispersion of water-repellent substance isbrought into contact with the creping roll,

since, owing to the absorption of water from the dispersion, the sidenot carrying the dispersion as well as the other side is adhesive to theroll.

The manufacture of waterproof or water-impermeable crepe-paper accordingto the inven tion is subject to several variations.

Thus, for example, a semi-finished, not or incompletely dried paper webcan be provided, while being on the paper making machinery, on one sideor, if desired, on bothsides with the dis persed waterrepellentsubstance and thereupon creped in the usualway, without previousdesiccation or after incomplete desiccation. I

In a similar way the creping can be performed on paper comprisingseveral layers with waterrepellent substance in between. An aqueousdispersion of water-repellent substance is then applied between thesemi-finished, wet paper layers which are then united to a compact paperweb, which without previous desiccation or after an incompletedesiccation, is subjected'to the creping treatment in a wet condition.In place of semi-finished paper layers it is also possible to producecrepe-paper comprising several layers by using webs of finished paper,between which the aqueous dispersion of water-repellent substance isapplied. The webs of paper then absorb the water from the dispersion,and are united by pressure to a single web with the water-repellentsubstance between the layers, this product being subsequently, eitherwithout previous drying 'or after partial drying, subjected in a wetcondition to the crepingtreatment.

According to the invention the creping can also .be performed onordinary, previously desiccated paper webs, after the latter beingtreated in some way or other as described above with an aqueousdispersion of water-repellent substance. In such cases the paper issufficiently moistened by the water ofthe dispersion applied on one sideor on both sides of the paper, or-between the instances, being creped inthe usual manner before desiccation or after partial desiccation.

When working up dispersions of asphalt or similar water-repellentsubstances according to the invention, it is preferable to use thosedispersions which coagulate only after extraction of the water, as isthe case, for example, with the dispersions of bituminous substances produced with clay as a dispersing-agent.

The waterproof or water-impermeable crepepapers produced according tothe invention have wide application. They are particularly suitable forthe manufacture of elastic and waterproof paper bags, for use aswaterproof and elastic packing-material and for decoration purposes. Inthe latter case they can be provided in the usual way with patterns, ordyed, which can be suitably done before the creping.

I claim as my invention:

1. A process of manufacturing waterproof crepe-paper comprisingincorporating an aqueous bituminous emulsion with fibrous pulp, formingthe mixture into a sheet and subjecting the sheet to a creping operationwhile in a moist condition, and subsequently drying the creped sheet toeffect coalescence of the emulsion.

2. A process of manufacturing waterproof crepe-paper which comprisescreping a web of fibrous material while in moist condition before it hasbeen completely dried on the paper machine and carrying aqueousbituminous emulsion, and subsequently drying the creped web to effectcoalescence of the emulsion.

FRIEDRICH MORJTZ O'I'I'O PINOFF.

